RESUMO -Objetivou-se avaliar o fornecimento de misturas de extratos vegetais nas dietas de frangos de corte.Utilizaram-se 1.350 aves distribuídas em blocos casualizados, com seis repetições e cinco dietas, uma sem aditivos e outras quatro, cada uma contendo um dos aditivos: 10 ppm de avilamicina; 200 ppm de um produto contendo óleos essenciais de cravo, tomilho, canela e pimenta; 100 ppm de um produto comercial composto de óleos essenciais sintéticos de orégano e canela e óleo-resina de pimenta microencapsulados; 500 ppm de um produto comercial constituído de óleo de eucalipto, óleo essencial de canela-da-china, folhas de boldo-do-chile e sementes de feno-grego na fase inicial e 1.200 ppm nas fases de crescimento e final. Aos 21 e 42 dias, foram avaliadas as variáveis de desempenho e aos 44 dias de idade, as características de carcaça. Dos 27 aos 30 dias de idade, foi realizado o ensaio de metabolismo pelo método de coleta total de excretas e determinadas a energia metabolizável e a digestibilidade da proteína bruta das dietas. As dietas com misturas de extratos vegetais não tiveram efeito significativo sobre o desempenho se comparadas à dieta sem aditivo e à dieta com antibiótico. A ausência de desafio na criação e a utilização de dietas com ingredientes de alta digestibilidade podem ter contribuído para que as aves expressassem todo o seu potencial, tornando indetectável a melhora ocasionada pela inclusão de qualquer dos aditivos. Dietas contendo misturas de extratos vegetais promovem desempenho semelhante ao obtido com dietas contendo antibiótico.Palavras-chaves: aditivos, características de carcaça, desempenho, ensaio de metabolismo Plant extracts in diets for broilersABSTRACT -The trial was carried out to evaluate different blends of plants extracts in broilers diets. It was used 1,350 broilers distributed in a randomized block design with six replicates and five diets, one without additive and the four others, each containing one of the following additives: 10 ppm of avilamycin; 200 ppm of a product containing essential oils of carnation, thyme, cinnamon and microencapsulated capsicum; 100 ppm of a product containing essential oils of synthetic cinnamaldehyde and carvacrol and capsicum oleoresin microencapsulated; 500 ppm of a commercial product containing eucalypt oil, essential oil of Chinese cinnamon, leaves of Chilene boldo and seeds of fenu-Greek at the initial phase and 1200 ppm in the grower and finisher phases. Performance parameters were evaluated at 21 and 42 days of age and the carcass characteristics at 44 days of age. From 27 to 30 days of age, it was carried out the metabolism trial trough total excreta collection method and metabolizable energy and the crude protein digestibility of the diets were determined. The diets with plant extract blends had no significant effect on the performance when compared to diet without additives or diet with avilamycin. The lack of challenge in the experimental facilities and the use of diets with high digestibility ingredients might have contributed to broil...
RESUMO -Avaliaram-se a digestibilidade ileal e a retenção de alguns nutrientes e os valores de energia de dietas contendo mananoligossacarídeo (MOS) e/ou complexo enzimático (CE) para frangos de corte. Foram utilizadas 275 aves em delineamento em blocos ao acaso e arranjo fatorial 2 x 2 + 1, com dois níveis de MOS (0 e 0,1%), dois níveis de complexo enzimático (0 e 0,05%) e uma dieta controle positivo com antibióticos. O óxido crômico (0,5%) foi adicionado às dietas para estimativa do fator de indigestibilidade. O experimento teve início quando as aves completaram 13 dias de idade; a coleta de excretas foi realizada do 20 o ao 22 o dia e a de digesta, no 23 o dia de idade das aves. A interação MOS × CE foi significativa para a retenção de PB e P e de energia metabolizável aparente (EMA), cujos valores foram maiores nas dietas com MOS e CE. A inclusão do CE melhorou a retenção de MS e os coeficientes de digestibilidade ileal de MS, PB, Ca e P na retenção de cálcio e nos valores de energia digestível com a inclusão de mananoligossacarídeo. Os coeficientes de digestibilidade ileal da MS, a retenção de MS, PB, Ca e P e os valores de energia digestível e de EMA das dietas contendo MOS e/ou CE foram superiores aos obtidos com a dieta contendo antibióticos.Palavras-chave: aditivos, enzimas, prebiótico, valor nutritivo Nutrients utilization from diets containing mannan oligosaccharides and/or enzymatic complex for broilersABSTRACT -The ileal digestibility and retention of some nutrients and the energy content were evaluated in diets for broilers containing mannan oligosaccharides (MOS) and/or enzymatic complex (EC). Two hundred and seventy-five birds were used in a randomized complete block design, with factorial arrangement (2 x 2 + 1) of the treatments, with two MOS levels (0 and 0.1%), two EC levels (0 and 0.05%) and a positive control diet with antibiotics. Chromic oxide (0.5%) was added to the diets to estimate the indigestibility factor. The experiment started when the birds reached 13 days of age, the excreta collection was performed from the 20 th to the 22 nd day and the digesta collection at the 23 rd day of age of the birds. The interaction MOS x EC was significant for CP and P retention and for apparent metabolizable energy (AME), whose values were higher in diets with MOS and EC. EC inclusion improved DM retention and there was an improvement on ileal digestibility coefficient of DM, CP, Ca and P, Ca retention, and digestible energy values due to MOS inclusion. Ileal digestibility coefficients of DM, and DM, CP, Ca and P retention, as well as AME values were higher in diets containing MOS and/or EC compared with the diets containing antibiotics.
Feed is responsible for about 70% of broilers production costs, leading to an increasing number of studies on alternative dietary products that benefit bird performance and lower production costs. Since the 1950s, antimicrobial additives are the most frequently used performance enhancers in animal production and their positive results are observed even in high-challenge conditions. Since the 1990s, due to the ban of the use of some antibiotics as growth promoters and the growing trend of the public to consume natural products, plant extracts have been researched as alternatives to antibiotic growth promoters. The first study that evaluated the antibacterial activities of plant extracts was carried out in 1881; however, they started to be used as flavor enhancers only during the next decades. With the emergence of antibiotics in the 1950s, the use of plant extracts as antimicrobial agents almost disappeared. There are several studies in literature assessing the use of plant extracts, individually or in combination, as antimicrobials, antioxidants, or digestibility enhancers in animal feeds. Research results on the factors affecting their action, such as plant variety, harvest time, processing, extraction, as well as the technology employed to manufacture the commercial product and dietary inclusion levels show controversial results, warranting the need of further research and standardization for the effective use of plant extracts as performance enhancers, when added to animal feeds. This article aims at presenting plant extracts as alternatives to antibiotics, explaining their main modes of action as performance enhancers in broiler production
Two experiments were carried out to determine which factor influences weight at hatch of broiler chicks: breeder age or incubated egg weight. In Experiment 1, 2340 eggs produced by 29-and 55-weekold Ross ® broiler breeders were incubated. The eggs selected for incubation weighed one standard deviation below and above average egg weight. In Experiment 2, 2160 eggs weighing 62 g produced by breeders of both ages were incubated. In both experiments, 50 additional eggs within the weight interval determined for each breeder age were weighed, broken, and their components were separated and weighed. At hatch, hatchlings were sexed and weighed, determining the average initial weight of the progeny of each breeder age. Data were analyzed using the Analyst program of SAS ® software package. In Experiment 1, the weight difference between eggs produced by young and mature breeders was 10.92 g, and the component that mostly influenced this difference was the yolk (7.51 g heavier in mature breeders, compared with 4.23 g difference in albumen and 0.8 g in eggshell weights). Hatchling weight difference was 9.4 g higher in eggs from mature breeders. In Experiment 2, egg weight difference was only 0.74 g, but yolk weight was 4.59 g higher in the eggs of mature breeders. The results obtained in the present study indicate that hatchling weight is influenced by egg weight, and not by breeder age. INTRODUCTIONA chicken egg generally consists of 58.5% albumen, 31% yolk, and 10.5% shell, but this composition varies according to genetic strain and breeder age (Vieira & Moran, 1999).Chick weight at hatch is directly related to egg weight, corresponding to 62 to 76% of egg weight. This correlation between increases after the 11th day of incubation and may remain the same during the entire rearing period (Wilson, 1991).Breeder age strongly influences egg weight, as well as egg quality and composition. Young breeders tend to produce lighter eggs, and consequently, lighter day-old chicks (Dalanezi et al., 2004); however, egg with the same weight can be produced by breeders of different ages as well breeders of the same age can produce eggs with different weights. Some studies showed that chick weight is independent of breeder age and it is only influenced by egg weight (Pinchasov, 1991).Egg weight increases with breeder age due to the increase in yolk size, whereas the variation in the weight of the eggs produced by breeders of the same age results from an increase in albumen proportion (Lima et al., 2001). It must be mentioned that eggs with the same weight, independently of breeder age, produce day-old chicks with the same weight and quality. Mail Adress
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